Shinkan is a document handwritten by the emperor. There are only a few documents in which Shinseki (original handwriting) of emperors before the Medieval Period exists, and many of them have been designated as a national treasures or important cultural properties.
Shinkan which have been designated as national treasures
Emperor Saga's shinkan, Kojokaijo (Enryaku-ji Temple)
Emperor Takakura's shinkan, Shosoku (Ninna-ji Temple)
Emperor Gotoba's shinkan, Otein Okifumi (Minase-jingu Shrine)
Emperor Gosaga's shinkan, Shosoku (Ninna-ji Temple)
Emperor Kameyama's shinkan, Zenrin-ji Temple Gokigan Monan (Nanzen-ji Temple)
Emperor Gouda's shinkan, Kobo taishi den (Daikaku-ji Temple)
Emperor Gouda's shinkan, Tojikoryu jojokotogaki onsoejo (To-ji Temple)
Emperor Gouda's shinkan, Ontein yuigo (Daikaku-ji Temple)
Emperor Gouda's shinkan, Toryu shoryu kyokai (Daigo-ji Temple)
Emperor Godaigo's shinkan, Shitenno-ji engi (Shitenno-ji Temple)
Emperor Godaigo's Okifumi (Daitoku-ji Temple)
Emperor Godaigo's shinkan, Tencho injin (Daigo-ji Temple)
Sancho Shinkan (Maeda Ikutoku Kai) (Emperor Hanazono, including Emperor Fushimi's shinkan)
Kumano Kaishi (Nishi Hongan-ji Temple) (including Emperor Gotoba's shinkan)
Kumano kaishi (Yomei Bunko) (including Emperor Gotoba's shinkan)
Emperor Shomu' shinkan
Emperor Shomu was well known for a master of calligraphy in the Nara Period as well as Empress Komyo, and shinkan documents which are believed to have been handwritten by Emperor Shomu are as follows:
Zasshu (treasure of Shoso-in Temple)
In a Buddhist memorial service for late Emperor Shomu, Empress Komyo dedicated all rare treasure and bequest items to the Rushana Buddhist (盧舎那) Statue of the Todai-ji Temple, praying for the Emperor's soul to rest in peace.
This role is one of those rare and bequest items and is recorded in 'Kenmotsu cho.'
The text contains more than one hundred and forty poems which were excerpted from Buddhism related poems of the Six Dynasties, Sui, Tang in China, and it comes with a style of thirty "hari" (27 X 2135㎝) long scroll and eighteen letters per line written on Hakuma sukami paper in the square style of writing and the top and bottom of the scroll lined horizontally. There is a statement 'Excerption completed on September 8, Tenpei 3' in Okugaki (postscript), which tells that he completed this at the age of thirty one.
It is thought that his writing style was close to the Gakki ron which was developed by O Gishi (Wang Xi-zhi) and similar to Cho Suiryo (Chu Sui-liang.)
All excerpted poems have already disappeared in China, so they are quite valuable as literature and Buddhist materials. What Emperor Shomu in fact handwrote is just one letter '勅' included in '聖武天皇勅書' (national treasure) which is held at the Heiden-ji Temple in Shizuoka Prefecture.
Kengu kyo (Ojobu) (held in Todai-ji Temple, etc.)
Sutras that were hand copied on Dabishi (scented paper for writing) in large sized letters during the Nara Period
This has been thought to be handwritten by Emperor Shomu since olden times, and is called 'Ojobu' and regarded to be a rare and valuable document because of the large size letters, but the handwriting is different from 'Zasshu' stated above. It was handed over to Kaidan-in, Todai-ji Temple, and as kansu bon (scroll), is now held at Todai-ji Temple, Tokyo National Museum, Maeda Ikutoku Kai and Hakutsuru Museum, and also dankan is found in Kohitsu Tekagami.
Emperor Saga's shinkan
Emperor Saga is one of the Noshoka (master of calligraphy) called Sanpitsu (the three great calligraphers) along with Kukai and TACHIBANA no Hayanari, and calligraphy products believed to be Emperor Saga's shinkan are as follows:
Kojokaijo (held at Enryaku-ji Temple)
Kojokaijo is a notice which Emperor Saga wrote on behalf of the Chotei (the Imperial Court) at the time Saicho's disciple Kojo (monk) was to be conferred Bosatsu kai (Bodhisattva Precepts) on May 31, 823 at Enryaku-ji Temple.
The grounds for proof is Emperor Saga's shinkan, there is a description that '厳筆徴僧)が戒牒を書し給ひ,恩勅之を賜ふ' in the Denjutsu isshin kaimon which was composed by Kojo (Saicho's biography.)
It is in a grave and solemn style of writing together with Kaigyoso (楷行草) and it is assumed that he learnt it from Kukai.
Koku Cho shonin shi (哭澄上人詩) (held by an individual, hereditary item of the Shoren-in Temple)
It is a poem in Gogon Hairitsu (twelve phrases consisting of sixty letters) which was created by Emperor Saga to express his mourning for the death of Saicho in 822, and believed to be the Emperor's shinkan and a copied duplicate rather than his handwritten original document.
It is in the Sosho style of writing and full of elegance, and recognized as being in the Daishi style (Kukai's writing style.)
Rikyo Hyakuei dankan (李嶠百詠断簡) (imperial properties)
It is a dankan (fragmentary leaves of a book) which carry the copies of a hundred twenty poets written in gyosho (handwriting), which were created by Rikyo, a poet in the Tang Dynasty. The dankan is full of changing strokes and in pure Tang Dynasty style. Since olden times It has been believed to be Emperor Saga's shinkan, but in recent calligraphic history, it is thought to be different handwriting.